JP2005282481A - Canister - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase adsorption amount by equalizing temperature distribution of a canister at a time of adsorption and desorption. <P>SOLUTION: N-eicosane (melting point 36 degrees celsius) of which phase change temperature is higher than atmospheric temperature as phase change material absorbing and desorbing latent heat according to temperature change is microencapsulated by melamine or the like to be made into powder heat accumulating agent, and the same is extruded with binder to be made into a shaped heat accumulating agent A. Although shaped activated carbon is mixed and filled in a case 1 to make blend ratio of the shaped heat accumulating agent A average 20 wt%, the blend ratio continuously changes to be 30wt% at an atmospheric air release opening 6 side part and 10 wt% at a vapor flow inlet 4 side part. Since temperature at the atmospheric air release opening 6 side becomes the highest at a time of adsorption, temperature rise is suppressed by the shaped heat accumulating agent A, temperature distribution of each part is equalized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a canister that uses an adsorbent such as activated carbon used for, for example, treatment of evaporated fuel of an internal combustion engine for automobiles.

  For example, in an internal combustion engine for an automobile, a canister capable of adsorbing and desorbing fuel vapor is provided in order to prevent the fuel vapor evaporated from the fuel tank of the vehicle from being released to the outside. The generated fuel vapor is temporarily adsorbed, and during the subsequent operation, the adsorbed fuel components are desorbed together with fresh air and burned in the internal combustion engine. Here, in a canister using an adsorbent such as activated carbon, when adsorbing fuel vapor, since it is a so-called exothermic reaction, the temperature of the canister rises, and the adsorption performance decreases as the temperature rises, On the contrary, when the adsorbed fuel component is desorbed, it is a so-called endothermic reaction, so that it is known that the temperature of the canister decreases, and the desorption performance decreases as the temperature decreases.

  In order to suppress the temperature change during adsorption and desorption of such a canister, it has been conventionally studied to mix a heat storage agent with an adsorbent such as activated carbon. For example, Patent Document 1 discloses a canister in which a heat storage agent made of a substance having a large specific heat such as a metal is mixed with an adsorbent.

However, when a large amount of heat storage agent is blended in the canister, the proportion of the adsorbent necessary for the original adsorption action is relatively reduced. Recently, the use of a phase change material as the above heat storage agent has attracted attention. Has been. For example, in Patent Documents 2 and 3, a phase change material such as an aliphatic hydrocarbon that absorbs and releases latent heat in accordance with a phase change is enclosed in a microcapsule to form a powder heat storage agent. A heat storage agent is mixed with an adsorbent and molded integrally, or attached to the surface of a granular adsorbent (activated carbon) to form a latent heat storage adsorbent. According to such a heat storage agent using latent heat accompanying phase change, a relatively small amount of heat storage agent suppresses the temperature change associated with the adsorption and desorption of fuel vapor, thereby improving the adsorption performance and desorption performance. I can plan.
JP 2001-248504 A JP 2001-145832 A JP 2003-31118 A

  The canister is provided with an inflow / outflow portion of steam at one end in the flow direction of the flow path in the case configured in a linear shape or a U-turn shape and the like, and an air opening is provided at the other end. , Gradually proceeds from the inlet / outlet side to the atmosphere opening side, and conversely, the desorption of the vapor gradually proceeds from the atmosphere opening side to the inlet / outlet side. Therefore, the temperature distribution of the canister during adsorption and desorption is not uniform. Therefore, if the heat storage agent is blended uniformly in each part, the improvement in the amount of adsorption due to the heat storage action is not necessarily the best.

  In addition, heat storage agents that use latent heat that accompanies phase change cannot absorb or release heat unless phase change occurs due to temperature changes in the canister. It is inherently difficult to obtain both the effects of suppressing the decrease. From the relationship between the phase change temperature and the ambient temperature under the use conditions of the canister, it is only possible during adsorption or desorption. An effect will be obtained. Therefore, it is necessary to use it as a heat storage agent for a canister in consideration of the properties peculiar to such a phase change material.

  The canister of the present invention mixes a heat storage agent using a phase change material that absorbs and releases latent heat according to a temperature change with an adsorbent and fills the case with the inflow / outflow of steam at one end in the flow direction. An outflow part is provided, and an air opening is provided at the other end, and in particular, the mixing ratio of the heat storage agent is not uniform, and the flow between the inflow / outflow part side and the air opening side The blending ratio of the heat storage agent changes along the direction.

  That is, in consideration of the temperature distribution of the canister at the time of vapor adsorption or desorption, the mixing ratio of the heat storage agent is optimal in each part.

  In the present invention, preferably, a heat storage agent having a phase change temperature higher than the atmospheric temperature under the use conditions of the canister is used, and the blending ratio of the heat storage agent is relatively high on the atmosphere opening side.

  Or while using the thermal storage agent whose phase change temperature is lower than the atmospheric temperature of the use conditions of a canister, the mixture ratio of this thermal storage agent is relatively high in the said inflow / outflow part side.

  That is, at the time of adsorption which is an exothermic reaction, the temperature of the adsorbent, that is, the temperature of the canister rises. In order to suppress the temperature rise at the time of adsorption by the heat storage agent using latent heat, the phase change (for example, solid phase) is performed before the phase change (for example, solid phase) in the temperature state close to the atmospheric temperature before adsorption, and the phase change (for example, by the temperature increase by adsorption) Therefore, as the heat storage agent, a heat storage agent having a phase change temperature higher than the atmospheric temperature assumed under the use conditions of the canister is necessary. In general, at the time of adsorption, the temperature on the air opening side rises highest, but if a large amount of heat storage agent is added to the air opening side, the amount of heat that can be absorbed as latent heat increases. Therefore, the temperature of each part of the canister at the time of adsorption approaches a more uniform temperature distribution.

  On the other hand, at the time of desorption that is an endothermic reaction, the temperature of the adsorbent, that is, the temperature of the canister, decreases. In order to suppress this temperature drop during desorption with a heat storage agent using latent heat, the phase is changed before the phase change (for example, liquid phase) in the temperature state close to the ambient temperature before desorption, and the phase decreases due to the temperature decrease due to desorption. Since it is necessary to change (for example, change to a solid phase), as the heat storage agent, a heat storage agent having a phase change temperature lower than the atmospheric temperature assumed under the use conditions of the canister is required. In general, the temperature on the inflow / outflow part side is the lowest at the time of desorption, but if a large amount of heat storage agent is added to the inflow / outflow part side, the amount of heat that can be released as latent heat increases. Therefore, the temperature of each part of the canister at the time of desorption approaches a more uniform temperature distribution.

  Moreover, in this invention, it is desirable for the mixture ratio (ratio of the heat storage agent with respect to the total amount of an adsorbent and a heat storage agent) of each part to exist in the range of 0-40 wt%. If the amount of the heat storage agent is excessively large, the ratio of the adsorbent having the original adsorption action is relatively reduced, and even if the temperature change is suppressed, it is disadvantageous in terms of the adsorption amount.

  In one aspect of the present invention, the inside of the case is partitioned into a plurality of regions along the flow direction, and the blending ratio changes stepwise so that the blending ratio of the heat storage agent is different in each region. Yes. There may be a region in which only the adsorbent that does not mix the heat storage agent is accommodated.

  Each region may be physically partitioned by a partition wall through which gas can flow, or may be configured to be partitioned into a plurality of regions without having a physical partition wall.

  Moreover, in one aspect of the present invention, the blending ratio of the heat storage agent is continuously changed along the flow direction without being clearly divided into a plurality of regions.

  The heat storage agent is not particularly limited as long as it uses a phase change material that absorbs and releases latent heat according to a temperature change, and various forms can be used. However, for example, a fine heat storage agent in which a phase change material that absorbs and releases latent heat in response to a temperature change as disclosed in Patent Document 2 or Patent Document 3 is enclosed in a microcapsule. Can be used.

  Preferably, the heat storage agent comprises a molded heat storage agent in which a fine heat storage agent formed by encapsulating a phase change substance in a microcapsule is molded into a particle together with a binder, and the molded heat storage agent is a granular adsorbent. Used in combination with.

The microencapsulated fine heat storage agent is known from Patent Document 2 or Patent Document 3 described above, and the phase change material is composed of, for example, an organic compound and an inorganic compound having a melting point of 10 ° C. to 80 ° C. For example, linear aliphatic hydrocarbons such as tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heikosan, docosan, natural wax, petroleum wax, LiNO ₃ .3H ₂ O, Na ₂ SO ₄ .10H ₂ O Hydrates of inorganic compounds such as Na ₂ HPO ₄ · 12H ₂ O, fatty acids such as capric acid and lauric acid, higher alcohols having 12 to 15 carbon atoms, esters such as methyl palmitate and methyl stearate It is done. The phase change material may be used in combination of two or more compounds selected from the above. And these can be used as core materials, and microcapsules can be used by a known method such as a coacervation method or an in-situ method (interface reaction method). As the outer shell of the microcapsule, known materials such as melamine, gelatin, and glass can be used. The particle size of the microencapsulated heat storage agent is preferably about several μm to several tens of μm. If the microcapsule is too small, the proportion of the outer shell constituting the capsule increases, and the proportion of the phase change material that repeats dissolution and solidification relatively decreases, so the amount of heat storage per unit volume of the powdered heat storage agent is reduced. descend. On the contrary, even if the microcapsule is excessively large, the strength of the capsule becomes necessary, so the ratio of the outer shell constituting the capsule also increases, and the heat storage amount per unit volume of the powder heat storage agent decreases. .

  In the present invention, preferably, the above microencapsulated powder heat storage agent is molded into an appropriate shape and size together with a binder to obtain a granular shaped heat storage agent. By molding only the heat storage agent in this way, the destruction of the microcapsules during molding is minimized. Various binders can be used, but a thermosetting resin such as a phenol resin or an acrylic resin is preferable in terms of stability and strength with respect to temperature and solvent required as a final canister. And by using this granular shaped heat storage agent mixed with the same granular adsorbent, separation of the two when subjected to vibration can be suppressed while ensuring the desired heat storage effect. Furthermore, an appropriate gap is secured between the granular shaped heat storage agent and the adsorbent, so that the adsorption / desorption action is not impaired and the pressure loss as a canister is small. Further, since the outer surface of the adsorbent is not covered with the powder heat storage agent, there is no adverse effect such as a decrease in the adsorption rate. The particle diameter of the granular shaped heat storage agent is, for example, about several hundred μm to several mm.

  The size of the granular shaped heat storage agent and the size of the granular adsorbent should be the same or approximate as much as possible in order to prevent separation of both of them over time and to ensure an appropriate flow path for gas flow. It is desirable to be. Specifically, the average particle size of the molded heat storage agent is desirably 10% to 300% of the average particle size of the adsorbent, and the average particle size of the molded heat storage agent is 50% of the average particle size of the adsorbent. More desirably, it is ˜150%.

  Various known materials can be used as the adsorbent, and for example, activated carbon can be used. And what was individually shape | molded to the predetermined dimension may be used, or you may classify | categorize and use adsorbents, such as crushed activated carbon, for a predetermined mesh. Similarly, the granular shaped heat storage agent can be formed into a predetermined size from the beginning, and can be used after being crushed into a large size.

  As a preferable shape, the molded heat storage agent and the adsorbent each have a cylindrical shape having a diameter of 1 to 3 mm and a length of 1 to 5 mm. This cylindrical shaped heat storage agent and adsorbent can be easily obtained by, for example, cutting or breaking a continuously extruded material. By combining such cylindrical objects, separation of both over time is more reliably suppressed.

  According to the present invention, at the time of adsorption or desorption, the temperature distribution of the canister can be suppressed more uniformly by suppressing the increase in temperature due to the absorption of latent heat or the decrease in temperature due to the release of latent heat. Thus, the adsorption amount can be improved.

  Hereinafter, specific examples of the present invention will be described.

  6.5 g of 37% formaldehyde aqueous solution and 10 g of water were added to 5 g of melamine powder and the pH was adjusted to 8, and then heated to about 70 ° C. to obtain an aqueous solution of melamine-formaldehyde initial condensate.

  While vigorously stirring the above melamine-formaldehyde initial condensate aqueous solution, a mixed solution prepared by dissolving 80 g of n-eicosane as a phase change substance in 100 g of a sodium salt aqueous solution of a styrene anhydride copolymer adjusted to pH 4.5. After addition and emulsification, the pH was adjusted to 9 and encapsulation was performed. The solvent of the capsule dispersion was removed by drying to obtain an n-eicosane microcapsule powder (heat storage agent) covered with a melamine film. The phase change temperature, that is, the melting point of n-eicosane is 36 ° C., which is higher than the atmospheric temperature when the atmospheric temperature under the use condition of the canister is assumed to be 25 ° C.

  A carboxymethyl cellulose aqueous solution as a binder is added to this powder heat storage agent and mixed, then extruded into a cylindrical shape, dried and cut to form a cylindrical shape having a diameter of about 2 mm and a length of 1 to 5 mm. A heat storage agent (A) was obtained.

  In addition, a wood-based activated carbon molded into a cylindrical shape having a diameter of about 2 mm and a length of 1 to 5 mm was obtained by the same extrusion molding.

  As shown in FIG. 1, an adsorbent made of nylon resin was mixed so that the above-mentioned molded heat storage agent (A) was 20 wt% and the above-mentioned molded activated carbon was 80 wt% as an average blending ratio. A case 1 having a capacity of 900 cc was filled to obtain a canister. In particular, at the left end of the figure provided with the steam inlet 4 and the steam outlet 5, the molded heat storage agent (A) is 10 wt%, the molded activated carbon is 90 wt%, and the right side of the figure provided with the atmosphere opening 6 At the end, the molded heat storage agent (A) was 30 wt% and the molded activated carbon was 70 wt%, and the blending ratio of the molded heat storage agent (A) was continuously changed between the two. Accordingly, in the central portion of the case 1 in the longitudinal direction, the molded heat storage agent (A) is 20 wt% and the molded activated carbon is 80 wt%.

  In addition, such a continuously changing distribution is such that when the case 1 is filled, the molded heat storage agent (A) and the molded activated carbon are mixed while being mixed, and the supply rates of both are being filled. It can be easily realized by changing to.

Using the same molded heat storage agent (A) and molded activated carbon as in Example 1, as shown in FIG. 2, the molded heat storage agent (A) is divided into three regions along the flow direction as shown in FIG. The blending ratio was changed stepwise. What was uniformly mixed at a rate of 10 wt% of the molded heat storage agent (A) and 90 wt% of the molded activated carbon was filled in the first region 11 on the steam inlet 4 side and the steam outlet 5 side, and the molded heat storage agent (A ) 20 wt% and molded activated carbon 80 wt% uniformly mixed in the second region 12 in the center, molded heat storage agent (A) 30 wt%, molded activated carbon 70 wt% The uniformly mixed material was filled in the third region 13 on the atmosphere opening 6 side.
(Comparative Example 1)
Only the cylindrical wood-based molded activated carbon used in Examples 1 and 2 was filled in the same nylon resin case 1 as in Examples 1 and 2 to obtain a canister.
(Comparative Example 2)
Fill the entire case 1 made of the same nylon resin as in Examples 1 and 2 with 20 wt% of the same molded heat storage agent (A) as in Examples 1 and 2 and 80 wt% in the ratio of molded activated carbon. And got the canister.

  FIG. 3 shows a more specific structure of the canister. The case 1 has a cylindrical shape, one end is closed by the inflow / outflow part side end wall 2 and the other end is opened to the atmosphere. It is blocked by the side end wall 3. A steam inlet 4 connected to the fuel tank and a steam outlet 5 connected to the engine intake passage are formed side by side on the inflow / outflow portion side end wall 2. Is formed with an air opening 6 that is open to the atmosphere. Inside the inflow / outflow portion side end wall 2, a perforated plate 8 having a flange on the periphery and a sheet-like filter member 9 made of nonwoven fabric or the like are disposed so as to leave a space 7. Similarly, a flat porous plate 21 and a sheet-like filter member 22 are arranged on the inner side of the end wall 3 on the air opening side, leaving a gap as a space 23, and two sheet-like filter members are arranged. Between 9 and 22 is an adsorbent accommodating space 10 filled with an adsorbent. A plurality of compression coil springs 24 are disposed between the air opening side end wall 3 and the perforated plate 21, whereby an appropriate pressing force is applied to the adsorbent filled in the adsorbent accommodating space 10. Has been granted.

  In Example 1, as described above, the blending ratio of the molded activated carbon filled in the adsorbent accommodating space 10 and the molded heat storage agent (A) continuously changes. Further, in Example 2, as described above, the adsorbent accommodating space 10 is partitioned into the first region 11 to the third region 13, and each of them is filled with a molded heat storage agent and a molded activated carbon having different blending ratios. However, as shown in FIG. 3, a physical partition wall is not necessarily required between the regions.

  FIG. 4 shows different specific examples of the canister, and in this configuration example, physical molding heat storage agents are not mixed between a plurality of regions having different blending ratios in stages. A partition wall 26 is provided. The partition wall 26 is made of a circular filter member having air permeability such as a nonwoven fabric and is interposed between adjacent regions, but is not particularly fixed to the case 1. FIG. 4 illustrates the configuration partitioned into two regions by the partition wall 26, but it is possible to partition into three or more regions as in the second embodiment.

  Further, as shown in FIG. 5, the present invention can be similarly applied to a canister having a U-turn channel. That is, in this configuration example, the case 1 has a rectangular parallelepiped shape as a whole and is divided into a first case part 32 in the upper part of the figure and a second case part 33 in the lower part of the figure by an intermediate partition wall 31. Each of the first and second case portions 32 and 33 has a cylindrical shape with a rectangular cross section. One end of the first case portion 32 is closed by the inflow / outflow portion side end wall 2 and the second case portion 33. Is closed by the atmosphere opening port side end wall 3. A steam inlet 4 connected to the fuel tank and a steam outlet 5 connected to the engine intake passage are formed side by side on the inflow / outflow portion side end wall 2. Is formed with an air opening 6 that is open to the atmosphere. That is, these three members are arranged on the same surface of the case 1. A perforated plate 8 and a sheet-like filter member 9 are disposed inside the inflow / outflow portion side end wall 2 so as to leave a space to be a space 7. Similarly, on the inner side, the plate-like perforated plate 21 and the sheet-like filter member 22 are disposed so as to overlap each other, leaving a gap as a space 23.

  In addition, a communication member end wall 34 is attached to the other end of the case 1, and a filter member 35 made of nonwoven fabric or the like is disposed so as to cover the other end opening surfaces of the first and second case portions 32 and 33. Has been. The filter member 35 is supported by a plurality of projecting portions 34 a provided on the communication portion end wall 34, whereby the first case portion 32 is interposed between the communication portion end wall 34 and the filter member 35. A space 36 is formed as a communication path that communicates with the second case portion 33. Accordingly, the first adsorbent accommodating space 10 a sandwiched between the two filter members 35, 9 is configured in the first case portion 32, and the two filter members 35, 22 are formed in the second case portion 33. A sandwiched second adsorbent accommodating space 10b is configured, and these two adsorbent accommodating spaces 10a and 10b are connected substantially in series as flow paths. A plurality of compression coil springs 24 are disposed between the air release port side end wall 3 and the perforated plate 21 and between the inflow / outflow portion side end wall 2 and the perforated plate 8. Yes.

  Even in such a U-turn canister, the essence as a canister is not different from that of a linear canister as shown in FIGS. 3 and 4, and the heat storage agent of Example 1 or Example 2 is used. Can be applied as well.

  FIG. 6 shows an example in which the compounding ratio distribution of Example 1 is applied as the U-turn canister. Similarly, FIG. 7 shows an example in which the distribution of the blending ratio of Example 2 is applied as the U-turn canister.

  When the amount of adsorption of the canister was measured using each of the above Examples and Comparative Example 2, a result as shown in FIG. 8 was obtained.

  That is, in Examples 1 and 2 in which the molded heat storage agent (A) was blended in an optimal distribution as compared with Comparative Example 2 in which the molded heat storage agent (A) was uniformly blended with the molded activated carbon, the molded heat storage agent (A) In spite of the same amount used, the amount of adsorption was greatly improved.

  In addition, the measurement direction of the adsorption amount is as follows. First, a test canister is connected to the fuel container 53 of the test circuit 51 shown in FIG. 9 at an ambient temperature of 25 ° C., and air at a predetermined flow rate (1.0 L / min) is passed through the inlets 52 a and 52 b of the air flow meter 52. Is blown into the liquid fuel (gasoline) 53a in the fuel container 53 to generate bubbling, and the fuel vapor 53b is adsorbed to the canister. Then, leakage (breakthrough) from the atmosphere opening 6 side of the canister is measured by the leakage detection device 54 and adsorbed until the leakage amount becomes 2.0 g. Next, the canister is replaced with the test circuit 61 shown in FIG. 10, and air is conveyed from the atmosphere opening 6 side to the canister using the vacuum pump 62 and the air flow meter 63 to desorb gasoline vapor. The above adsorption / desorption of gasoline vapor was repeated 6 times, and the adsorption amount of gasoline vapor in the last 3 times was averaged to obtain the adsorption amount of each canister.

  FIG. 11 shows the results of measuring the temperature distribution of each part in the canister, particularly the temperature distribution at the end of adsorption, for Examples 1 and 2 and Comparative Examples 1 and 2. The temperature inside the canister is basically higher than the ambient temperature (25 ° C.) during adsorption and higher toward the atmosphere opening 6 side, as seen in Comparative Example 1 using only molded activated carbon. Become. The phase change material of the molding heat storage agent (A) having a melting point of 36 ° C. is a solid phase under the atmospheric temperature, and when the temperature rises above the melting point, it absorbs latent heat and changes into a liquid phase. In Examples 1 and 2 and Comparative Example 2 containing the agent (A), the temperature is suppressed to be lower than that of Comparative Example 1 due to the latent heat absorption action. Here, in Examples 1 and 2, the amount of heat that can be absorbed by the molded heat storage agent (A) at the portion of the atmosphere opening 6 side where the temperature rise is most remarkable is larger than that of Comparative Example 2, and therefore this atmosphere opening The temperature at the 6-side portion can be suppressed lower than that in Comparative Example 2. For this reason, it is possible to suppress a decrease in the adsorption performance of the adsorbent at the air opening 6 side portion. As for the steam inlet 4 and the steam outlet 5 side, Examples 1 and 2 are higher in temperature than Comparative Example 2 because there is less molded heat storage agent (A), but the absolute temperature itself is atmospheric. Since it is lower than the opening 6 side portion, the adverse effect on the adsorption amount of the entire canister is relatively small, and the adsorption amount of the entire canister is improved as compared with Comparative Example 2 as described above.

  As shown in FIG. 12, in a U-turn canister, only the above-mentioned molded activated carbon is filled in the first adsorbent housing space 10a, and the above-mentioned molded heat storage agent (A) and molded activated carbon are mixed. The second adsorbent accommodating space 10b was filled. In particular, in the second adsorbent accommodating space 10b, at the end portion on the side of the communication path (space 36) connected to the first adsorbent accommodating space 10a, the molded heat storage agent (A) is 0 wt%, the molded activated carbon is 100 wt%, Thus, at the end of the atmosphere opening 6 side, the molded heat storage agent (A) is 40 wt%, the molded activated carbon is 60 wt%, and the blending ratio of the molded heat storage agent (A) continuously changes between the two. did. Therefore, the average blending ratio of the canister as a whole is 10 wt% for the molded heat storage agent (A) and 90 wt% for the molded activated carbon. The molded activated carbon in the first adsorbent accommodating space 10a functions as a pretreatment layer when the activated carbon is significantly deteriorated due to, for example, use of poor fuel. In this case, the molded heat storage agent (A) in the entire canister is reduced accordingly. Of course, the canister is not limited to the U-turn canister, and can be configured as the linear canister described above.

  By the same method as in Example 1 above, a cylindrical shaped heat storage agent (B) was obtained using n-hexadecane as the phase change material. The phase change temperature, that is, the melting point of n-hexadecane is 16 ° C., which is lower than the atmospheric temperature (25 ° C.) assumed under the use conditions of the canister.

  As shown in FIG. 13, a case 1 made of nylon resin was mixed so that the above-mentioned molded heat storage agent (B) was 20 wt% and the above-mentioned molded activated carbon was 80 wt%. The canister was obtained. In particular, at the left end of the figure with the steam inlet 4 and the steam outlet 5, the molded heat storage agent (B) is 30 wt%, the molded activated carbon is 70 wt%, and the right side of the figure with the air opening 6 is provided. At the end, the molded heat storage agent (B) was 10 wt% and the molded activated carbon was 90 wt%, and the blending ratio of the molded heat storage agent (B) was continuously changed between the two. Therefore, in the central part of the case 1 in the longitudinal direction, the molded heat storage agent (B) is 20 wt% and the molded activated carbon is 80 wt%. That is, in Example 4, the increase / decrease direction of the molded heat storage agent is reversed compared to Example 1.

  FIG. 14 shows the results of measuring the temperature distribution of each part in the canister, particularly the temperature distribution at the end of desorption, for Example 4 and Comparative Example 1. The temperature in the canister is basically lower than the ambient temperature (25 ° C.) at the time of desorption and lower at the vapor outlet 5 side, as seen in Comparative Example 1 using only molded activated carbon. It becomes. The phase change material of the molded heat storage agent (B) having a melting point of 16 ° C. is a liquid phase under the atmospheric temperature, and when the temperature falls below the melting point, it releases latent heat and changes into a solid phase. Example 4 containing the agent (B) is kept at a higher temperature than Comparative Example 1 due to its latent heat release action. Here, in Example 4, since the blending ratio of the molded heat storage agent (B) is high in the steam outlet 5 side portion where the temperature drop is most remarkable, the temperature drop in this portion can be more reliably suppressed. Therefore, desorption at the vapor outlet 5 side portion is sufficiently performed, and a decrease in the adsorption performance of the adsorbent at the portion can be suppressed.

  As shown in FIG. 15, in a U-turn canister, only the above-mentioned molded activated carbon is filled in the first adsorbent housing space 10a, and the above-mentioned molded heat storage agent (B) and molded activated carbon are mixed. The second adsorbent accommodating space 10b was filled. In particular, in the second adsorbent accommodating space 10b, at the end on the side of the communication path (space 36) connected to the first adsorbent accommodating space 10a, the molded heat storage agent (B) is 40 wt%, the molded activated carbon is 60 wt%, Thus, at the end of the atmosphere opening 6 side, the molded heat storage agent (B) is 0 wt% and the molded activated carbon is 100 wt%, so that the blending ratio of the molded heat storage agent (B) continuously changes between them. did. Therefore, the average blending ratio of the entire canister is 10 wt% for the molded heat storage agent (B) and 90 wt% for the molded activated carbon. As in Example 3, Example 5 functions as a pretreatment layer when the molded activated carbon in the first adsorbent accommodation space 10a is significantly deteriorated due to, for example, use of poor fuel. is there. Of course, the canister is not limited to the U-turn canister, and can be configured as the linear canister described above.

  As described above, each example using n-eicosane (melting point: 36 ° C.) and n-hexadecane (melting point: 16 ° C.) as the phase change material has been described assuming that the atmospheric temperature under the use condition of the canister is 25 ° C. Needless to say, the ambient temperature may be higher or lower depending on the arrangement of the canister in the automobile. Therefore, as the phase change material, the adsorption or desorption may be performed based on the assumed ambient temperature. It is appropriately selected so that a phase change occurs at the time of separation.

2 is an explanatory diagram of a canister according to Embodiment 1. FIG. FIG. 6 is an explanatory diagram of a canister according to a second embodiment. Sectional drawing which shows the more concrete structure of a canister. Sectional drawing which shows the example from which the concrete structure of a canister differs. Sectional drawing which shows the further different example of the concrete structure of a canister. Explanatory drawing of the canister of Example 1 made into U-turn shape. Explanatory drawing of the canister of Example 2 made into U-turn shape. The characteristic view which shows the adsorption amount of an Example and a comparative example. Explanatory drawing which shows the test circuit at the time of adsorption | suction. Explanatory drawing which shows the test circuit at the time of detachment | desorption. The characteristic view which shows the temperature distribution at the time of completion | finish of adsorption | suction of an Example and a comparative example. FIG. 6 is an explanatory diagram of a canister according to a third embodiment. FIG. 6 is an explanatory diagram of a canister according to a fourth embodiment. The characteristic view which shows the temperature distribution at the time of completion | finish of detachment | desorption of Example 4 and a comparative example. FIG. 10 is an explanatory diagram of a canister according to a fifth embodiment.

Explanation of symbols

1 ... Case 4 ... Vapor inlet 5 ... Vapor outlet 6 ... Open to atmosphere

Claims (8)

A heat storage agent using a phase change material that absorbs and releases latent heat according to temperature changes is mixed with the adsorbent and filled in the case, and a steam inflow / outflow section is provided at one end in the flow direction, and In a canister with an air opening at the other end,
The canister, wherein a blending ratio of the heat storage agent is changed along a flow direction between the inflow / outflow part side and the atmosphere opening side.   The heat storage agent having a phase change temperature higher than the atmospheric temperature under the use condition of the canister is used, and the blending ratio of the heat storage agent is relatively high on the atmosphere opening side. Canister as described in   The heat storage agent having a phase change temperature lower than the atmospheric temperature under the use conditions of the canister is used, and the blending ratio of the heat storage agent is relatively high on the inflow / outflow side. The canister according to 1.   The canister according to any one of claims 1 to 3, wherein the proportion of the heat storage agent in each part is in the range of 0 to 40 wt%.   The inside of the case is divided into a plurality of regions along the flow direction, and the blending ratio changes stepwise so that the blending ratio of the heat storage agent is different in each region. The canister according to any one of 1 to 4.   The canister according to claim 5, comprising a region in which only the adsorbent that does not mix the heat storage agent is accommodated.   The canister according to any one of claims 1 to 4, wherein a blending ratio of the heat storage agent continuously changes along the flow direction.   The heat storage agent is composed of a molded heat storage agent in which a fine heat storage agent formed by encapsulating a phase change material in a microcapsule is molded in a granular form together with a binder, and this molded heat storage agent is used by mixing with a granular adsorbent. The canister according to claim 1, wherein the canister is formed.

Images